This invention relates to a method of making a joint between a small diameter metal tube and a large diameter metal tube and particularly when the tubes are of dissimilar metals. More particularly, this invention relates to making a joint between a capillary tube and an evaporator or condenser tube of a refrigerating system.
Joining of the capillary tube to either the evaporator tube or condenser tube which are considerably larger in diameter than the capillary tube has been done by using a intermediate cylindrical sleeve and then silver-soldering the components together. By so soldering, mechanical strength of the joint is achieved and also there is electrical continuity from the capillary tube through the sleeve to the evaporator or condenser tube for grounding purposes in accordance with various safety codes to prevent electrical shock hazard. Silver-soldering of the capillary to the evaporator or condenser tube has certain drawbacks, one of which is that the heat necessary to achieve the soldering operation can collapse the very small diameter capillary tube and thus make it inoperative in the refrigerating system. Silver-soldering is also an expensive operation both as the equipment and the materials involved.
By this invention, there is provided a method of making a joint between a small diameter tube and a large diameter tube such as between a capillary tube and a evaporator or condenser tube and that joint is made with adhesive and is mechanically strong and also has electrical continuity for grounding the joined tubes.